arch/powerpc/platforms/pseries/ras.c - kernel/bruno - Git at Google

 /*
  * Copyright (C) 2001 Dave Engebretsen IBM Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */

 #include <linux/sched.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/of.h>
 #include <linux/fs.h>
 #include <linux/reboot.h>

 #include <asm/machdep.h>
 #include <asm/rtas.h>
 #include <asm/firmware.h>

 #include "pseries.h"

 static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
 static DEFINE_SPINLOCK(ras_log_buf_lock);

 static char global_mce_data_buf[RTAS_ERROR_LOG_MAX];
 static DEFINE_PER_CPU(__u64, mce_data_buf);

 static int ras_check_exception_token;

 #define EPOW_SENSOR_TOKEN	9
 #define EPOW_SENSOR_INDEX	0

 static irqreturn_t ras_epow_interrupt(int irq, void *dev_id);
 static irqreturn_t ras_error_interrupt(int irq, void *dev_id);


 /*
  * Initialize handlers for the set of interrupts caused by hardware errors
  * and power system events.
  */
 static int __init init_ras_IRQ(void)
 {
 	struct device_node *np;

 	ras_check_exception_token = rtas_token("check-exception");

 	/* Internal Errors */
 	np = of_find_node_by_path("/event-sources/internal-errors");
 	if (np != NULL) {
 		request_event_sources_irqs(np, ras_error_interrupt,
 					   "RAS_ERROR");
 		of_node_put(np);
 	}

 	/* EPOW Events */
 	np = of_find_node_by_path("/event-sources/epow-events");
 	if (np != NULL) {
 		request_event_sources_irqs(np, ras_epow_interrupt, "RAS_EPOW");
 		of_node_put(np);
 	}

 	return 0;
 }
 machine_subsys_initcall(pseries, init_ras_IRQ);

 #define EPOW_SHUTDOWN_NORMAL				1
 #define EPOW_SHUTDOWN_ON_UPS				2
 #define EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS	3
 #define EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH	4

 static void handle_system_shutdown(char event_modifier)
 {
 	switch (event_modifier) {
 	case EPOW_SHUTDOWN_NORMAL:
 		pr_emerg("Firmware initiated power off");
 		orderly_poweroff(true);
 		break;

 	case EPOW_SHUTDOWN_ON_UPS:
 		pr_emerg("Loss of power reported by firmware, system is "
 			"running on UPS/battery");
 		break;

 	case EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS:
 		pr_emerg("Loss of system critical functions reported by "
 			"firmware");
 		pr_emerg("Check RTAS error log for details");
 		orderly_poweroff(true);
 		break;

 	case EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH:
 		pr_emerg("Ambient temperature too high reported by firmware");
 		pr_emerg("Check RTAS error log for details");
 		orderly_poweroff(true);
 		break;

 	default:
 		pr_err("Unknown power/cooling shutdown event (modifier %d)",
 			event_modifier);
 	}
 }

 struct epow_errorlog {
 	unsigned char sensor_value;
 	unsigned char event_modifier;
 	unsigned char extended_modifier;
 	unsigned char reserved;
 	unsigned char platform_reason;
 };

 #define EPOW_RESET			0
 #define EPOW_WARN_COOLING		1
 #define EPOW_WARN_POWER			2
 #define EPOW_SYSTEM_SHUTDOWN		3
 #define EPOW_SYSTEM_HALT		4
 #define EPOW_MAIN_ENCLOSURE		5
 #define EPOW_POWER_OFF			7

 static void rtas_parse_epow_errlog(struct rtas_error_log *log)
 {
 	struct pseries_errorlog *pseries_log;
 	struct epow_errorlog *epow_log;
 	char action_code;
 	char modifier;

 	pseries_log = get_pseries_errorlog(log, PSERIES_ELOG_SECT_ID_EPOW);
 	if (pseries_log == NULL)
 		return;

 	epow_log = (struct epow_errorlog *)pseries_log->data;
 	action_code = epow_log->sensor_value & 0xF;	/* bottom 4 bits */
 	modifier = epow_log->event_modifier & 0xF;	/* bottom 4 bits */

 	switch (action_code) {
 	case EPOW_RESET:
 		pr_err("Non critical power or cooling issue cleared");
 		break;

 	case EPOW_WARN_COOLING:
 		pr_err("Non critical cooling issue reported by firmware");
 		pr_err("Check RTAS error log for details");
 		break;

 	case EPOW_WARN_POWER:
 		pr_err("Non critical power issue reported by firmware");
 		pr_err("Check RTAS error log for details");
 		break;

 	case EPOW_SYSTEM_SHUTDOWN:
 		handle_system_shutdown(epow_log->event_modifier);
 		break;

 	case EPOW_SYSTEM_HALT:
 		pr_emerg("Firmware initiated power off");
 		orderly_poweroff(true);
 		break;

 	case EPOW_MAIN_ENCLOSURE:
 	case EPOW_POWER_OFF:
 		pr_emerg("Critical power/cooling issue reported by firmware");
 		pr_emerg("Check RTAS error log for details");
 		pr_emerg("Immediate power off");
 		emergency_sync();
 		kernel_power_off();
 		break;

 	default:
 		pr_err("Unknown power/cooling event (action code %d)",
 			action_code);
 	}
 }

 /* Handle environmental and power warning (EPOW) interrupts. */
 static irqreturn_t ras_epow_interrupt(int irq, void *dev_id)
 {
 	int status;
 	int state;
 	int critical;

 	status = rtas_get_sensor(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, &state);

 	if (state > 3)
 		critical = 1;		/* Time Critical */
 	else
 		critical = 0;

 	spin_lock(&ras_log_buf_lock);

 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
 			   RTAS_VECTOR_EXTERNAL_INTERRUPT,
 			   virq_to_hw(irq),
 			   RTAS_EPOW_WARNING,
 			   critical, __pa(&ras_log_buf),
 				rtas_get_error_log_max());

 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);

 	rtas_parse_epow_errlog((struct rtas_error_log *)ras_log_buf);

 	spin_unlock(&ras_log_buf_lock);
 	return IRQ_HANDLED;
 }

 /*
  * Handle hardware error interrupts.
  *
  * RTAS check-exception is called to collect data on the exception.  If
  * the error is deemed recoverable, we log a warning and return.
  * For nonrecoverable errors, an error is logged and we stop all processing
  * as quickly as possible in order to prevent propagation of the failure.
  */
 static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
 {
 	struct rtas_error_log *rtas_elog;
 	int status;
 	int fatal;

 	spin_lock(&ras_log_buf_lock);

 	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
 			   RTAS_VECTOR_EXTERNAL_INTERRUPT,
 			   virq_to_hw(irq),
 			   RTAS_INTERNAL_ERROR, 1 /* Time Critical */,
 			   __pa(&ras_log_buf),
 				rtas_get_error_log_max());

 	rtas_elog = (struct rtas_error_log *)ras_log_buf;

 	if (status == 0 &&
 	    rtas_error_severity(rtas_elog) >= RTAS_SEVERITY_ERROR_SYNC)
 		fatal = 1;
 	else
 		fatal = 0;

 	/* format and print the extended information */
 	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);

 	if (fatal) {
 		pr_emerg("Fatal hardware error reported by firmware");
 		pr_emerg("Check RTAS error log for details");
 		pr_emerg("Immediate power off");
 		emergency_sync();
 		kernel_power_off();
 	} else {
 		pr_err("Recoverable hardware error reported by firmware");
 	}

 	spin_unlock(&ras_log_buf_lock);
 	return IRQ_HANDLED;
 }

 /*
  * Some versions of FWNMI place the buffer inside the 4kB page starting at
  * 0x7000. Other versions place it inside the rtas buffer. We check both.
  */
 #define VALID_FWNMI_BUFFER(A) \
 	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
 	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))

 /*
  * Get the error information for errors coming through the
  * FWNMI vectors.  The pt_regs' r3 will be updated to reflect
  * the actual r3 if possible, and a ptr to the error log entry
  * will be returned if found.
  *
  * If the RTAS error is not of the extended type, then we put it in a per
  * cpu 64bit buffer. If it is the extended type we use global_mce_data_buf.
  *
  * The global_mce_data_buf does not have any locks or protection around it,
  * if a second machine check comes in, or a system reset is done
  * before we have logged the error, then we will get corruption in the
  * error log.  This is preferable over holding off on calling
  * ibm,nmi-interlock which would result in us checkstopping if a
  * second machine check did come in.
  */
 static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
 {
 	unsigned long *savep;
 	struct rtas_error_log *h, *errhdr = NULL;

 	/* Mask top two bits */
 	regs->gpr[3] &= ~(0x3UL << 62);

 	if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
 		printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
 		return NULL;
 	}

 	savep = __va(regs->gpr[3]);
 	regs->gpr[3] = savep[0];	/* restore original r3 */

 	/* If it isn't an extended log we can use the per cpu 64bit buffer */
 	h = (struct rtas_error_log *)&savep[1];
 	if (!rtas_error_extended(h)) {
 		memcpy(this_cpu_ptr(&mce_data_buf), h, sizeof(__u64));
 		errhdr = (struct rtas_error_log *)this_cpu_ptr(&mce_data_buf);
 	} else {
 		int len, error_log_length;

 		error_log_length = 8 + rtas_error_extended_log_length(h);
 		len = max_t(int, error_log_length, RTAS_ERROR_LOG_MAX);
 		memset(global_mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
 		memcpy(global_mce_data_buf, h, len);
 		errhdr = (struct rtas_error_log *)global_mce_data_buf;
 	}

 	return errhdr;
 }

 /* Call this when done with the data returned by FWNMI_get_errinfo.
  * It will release the saved data area for other CPUs in the
  * partition to receive FWNMI errors.
  */
 static void fwnmi_release_errinfo(void)
 {
 	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
 	if (ret != 0)
 		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
 }

 int pSeries_system_reset_exception(struct pt_regs *regs)
 {
 	if (fwnmi_active) {
 		struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
 		if (errhdr) {
 			/* XXX Should look at FWNMI information */
 		}
 		fwnmi_release_errinfo();
 	}
 	return 0; /* need to perform reset */
 }

 /*
  * See if we can recover from a machine check exception.
  * This is only called on power4 (or above) and only via
  * the Firmware Non-Maskable Interrupts (fwnmi) handler
  * which provides the error analysis for us.
  *
  * Return 1 if corrected (or delivered a signal).
  * Return 0 if there is nothing we can do.
  */
 static int recover_mce(struct pt_regs *regs, struct rtas_error_log *err)
 {
 	int recovered = 0;
 	int disposition = rtas_error_disposition(err);

 	if (!(regs->msr & MSR_RI)) {
 		/* If MSR_RI isn't set, we cannot recover */
 		recovered = 0;

 	} else if (disposition == RTAS_DISP_FULLY_RECOVERED) {
 		/* Platform corrected itself */
 		recovered = 1;

 	} else if (disposition == RTAS_DISP_LIMITED_RECOVERY) {
 		/* Platform corrected itself but could be degraded */
 		printk(KERN_ERR "MCE: limited recovery, system may "
 		       "be degraded\n");
 		recovered = 1;

 	} else if (user_mode(regs) && !is_global_init(current) &&
 		   rtas_error_severity(err) == RTAS_SEVERITY_ERROR_SYNC) {

 		/*
 		 * If we received a synchronous error when in userspace
 		 * kill the task. Firmware may report details of the fail
 		 * asynchronously, so we can't rely on the target and type
 		 * fields being valid here.
 		 */
 		printk(KERN_ERR "MCE: uncorrectable error, killing task "
 		       "%s:%d\n", current->comm, current->pid);

 		_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
 		recovered = 1;
 	}

 	log_error((char *)err, ERR_TYPE_RTAS_LOG, 0);

 	return recovered;
 }

 /*
  * Handle a machine check.
  *
  * Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
  * should be present.  If so the handler which called us tells us if the
  * error was recovered (never true if RI=0).
  *
  * On hardware prior to Power 4 these exceptions were asynchronous which
  * means we can't tell exactly where it occurred and so we can't recover.
  */
 int pSeries_machine_check_exception(struct pt_regs *regs)
 {
 	struct rtas_error_log *errp;

 	if (fwnmi_active) {
 		errp = fwnmi_get_errinfo(regs);
 		fwnmi_release_errinfo();
 		if (errp && recover_mce(regs, errp))
 			return 1;
 	}

 	return 0;
 }
	/*
	* Copyright (C) 2001 Dave Engebretsen IBM Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/

	#include <linux/sched.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/of.h>
	#include <linux/fs.h>
	#include <linux/reboot.h>

	#include <asm/machdep.h>
	#include <asm/rtas.h>
	#include <asm/firmware.h>

	#include "pseries.h"

	static unsigned char ras_log_buf[RTAS_ERROR_LOG_MAX];
	static DEFINE_SPINLOCK(ras_log_buf_lock);

	static char global_mce_data_buf[RTAS_ERROR_LOG_MAX];
	static DEFINE_PER_CPU(__u64, mce_data_buf);

	static int ras_check_exception_token;

	#define EPOW_SENSOR_TOKEN 9
	#define EPOW_SENSOR_INDEX 0

	static irqreturn_t ras_epow_interrupt(int irq, void *dev_id);
	static irqreturn_t ras_error_interrupt(int irq, void *dev_id);


	/*
	* Initialize handlers for the set of interrupts caused by hardware errors
	* and power system events.
	*/
	static int __init init_ras_IRQ(void)
	{
	struct device_node *np;

	ras_check_exception_token = rtas_token("check-exception");

	/* Internal Errors */
	np = of_find_node_by_path("/event-sources/internal-errors");
	if (np != NULL) {
	request_event_sources_irqs(np, ras_error_interrupt,
	"RAS_ERROR");
	of_node_put(np);
	}

	/* EPOW Events */
	np = of_find_node_by_path("/event-sources/epow-events");
	if (np != NULL) {
	request_event_sources_irqs(np, ras_epow_interrupt, "RAS_EPOW");
	of_node_put(np);
	}

	return 0;
	}
	machine_subsys_initcall(pseries, init_ras_IRQ);

	#define EPOW_SHUTDOWN_NORMAL 1
	#define EPOW_SHUTDOWN_ON_UPS 2
	#define EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS 3
	#define EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH 4

	static void handle_system_shutdown(char event_modifier)
	{
	switch (event_modifier) {
	case EPOW_SHUTDOWN_NORMAL:
	pr_emerg("Firmware initiated power off");
	orderly_poweroff(true);
	break;

	case EPOW_SHUTDOWN_ON_UPS:
	pr_emerg("Loss of power reported by firmware, system is "
	"running on UPS/battery");
	break;

	case EPOW_SHUTDOWN_LOSS_OF_CRITICAL_FUNCTIONS:
	pr_emerg("Loss of system critical functions reported by "
	"firmware");
	pr_emerg("Check RTAS error log for details");
	orderly_poweroff(true);
	break;

	case EPOW_SHUTDOWN_AMBIENT_TEMPERATURE_TOO_HIGH:
	pr_emerg("Ambient temperature too high reported by firmware");
	pr_emerg("Check RTAS error log for details");
	orderly_poweroff(true);
	break;

	default:
	pr_err("Unknown power/cooling shutdown event (modifier %d)",
	event_modifier);
	}
	}

	struct epow_errorlog {
	unsigned char sensor_value;
	unsigned char event_modifier;
	unsigned char extended_modifier;
	unsigned char reserved;
	unsigned char platform_reason;
	};

	#define EPOW_RESET 0
	#define EPOW_WARN_COOLING 1
	#define EPOW_WARN_POWER 2
	#define EPOW_SYSTEM_SHUTDOWN 3
	#define EPOW_SYSTEM_HALT 4
	#define EPOW_MAIN_ENCLOSURE 5
	#define EPOW_POWER_OFF 7

	static void rtas_parse_epow_errlog(struct rtas_error_log *log)
	{
	struct pseries_errorlog *pseries_log;
	struct epow_errorlog *epow_log;
	char action_code;
	char modifier;

	pseries_log = get_pseries_errorlog(log, PSERIES_ELOG_SECT_ID_EPOW);
	if (pseries_log == NULL)
	return;

	epow_log = (struct epow_errorlog *)pseries_log->data;
	action_code = epow_log->sensor_value & 0xF; /* bottom 4 bits */
	modifier = epow_log->event_modifier & 0xF; /* bottom 4 bits */

	switch (action_code) {
	case EPOW_RESET:
	pr_err("Non critical power or cooling issue cleared");
	break;

	case EPOW_WARN_COOLING:
	pr_err("Non critical cooling issue reported by firmware");
	pr_err("Check RTAS error log for details");
	break;

	case EPOW_WARN_POWER:
	pr_err("Non critical power issue reported by firmware");
	pr_err("Check RTAS error log for details");
	break;

	case EPOW_SYSTEM_SHUTDOWN:
	handle_system_shutdown(epow_log->event_modifier);
	break;

	case EPOW_SYSTEM_HALT:
	pr_emerg("Firmware initiated power off");
	orderly_poweroff(true);
	break;

	case EPOW_MAIN_ENCLOSURE:
	case EPOW_POWER_OFF:
	pr_emerg("Critical power/cooling issue reported by firmware");
	pr_emerg("Check RTAS error log for details");
	pr_emerg("Immediate power off");
	emergency_sync();
	kernel_power_off();
	break;

	default:
	pr_err("Unknown power/cooling event (action code %d)",
	action_code);
	}
	}

	/* Handle environmental and power warning (EPOW) interrupts. */
	static irqreturn_t ras_epow_interrupt(int irq, void *dev_id)
	{
	int status;
	int state;
	int critical;

	status = rtas_get_sensor(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, &state);

	if (state > 3)
	critical = 1; /* Time Critical */
	else
	critical = 0;

	spin_lock(&ras_log_buf_lock);

	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
	RTAS_VECTOR_EXTERNAL_INTERRUPT,
	virq_to_hw(irq),
	RTAS_EPOW_WARNING,
	critical, __pa(&ras_log_buf),
	rtas_get_error_log_max());

	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);

	rtas_parse_epow_errlog((struct rtas_error_log *)ras_log_buf);

	spin_unlock(&ras_log_buf_lock);
	return IRQ_HANDLED;
	}

	/*
	* Handle hardware error interrupts.
	*
	* RTAS check-exception is called to collect data on the exception. If
	* the error is deemed recoverable, we log a warning and return.
	* For nonrecoverable errors, an error is logged and we stop all processing
	* as quickly as possible in order to prevent propagation of the failure.
	*/
	static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
	{
	struct rtas_error_log *rtas_elog;
	int status;
	int fatal;

	spin_lock(&ras_log_buf_lock);

	status = rtas_call(ras_check_exception_token, 6, 1, NULL,
	RTAS_VECTOR_EXTERNAL_INTERRUPT,
	virq_to_hw(irq),
	RTAS_INTERNAL_ERROR, 1 /* Time Critical */,
	__pa(&ras_log_buf),
	rtas_get_error_log_max());

	rtas_elog = (struct rtas_error_log *)ras_log_buf;

	if (status == 0 &&
	rtas_error_severity(rtas_elog) >= RTAS_SEVERITY_ERROR_SYNC)
	fatal = 1;
	else
	fatal = 0;

	/* format and print the extended information */
	log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, fatal);

	if (fatal) {
	pr_emerg("Fatal hardware error reported by firmware");
	pr_emerg("Check RTAS error log for details");
	pr_emerg("Immediate power off");
	emergency_sync();
	kernel_power_off();
	} else {
	pr_err("Recoverable hardware error reported by firmware");
	}

	spin_unlock(&ras_log_buf_lock);
	return IRQ_HANDLED;
	}

	/*
	* Some versions of FWNMI place the buffer inside the 4kB page starting at
	* 0x7000. Other versions place it inside the rtas buffer. We check both.
	*/
	#define VALID_FWNMI_BUFFER(A) \
	((((A) >= 0x7000) && ((A) < 0x7ff0)) \|\| \
	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))

	/*
	* Get the error information for errors coming through the
	* FWNMI vectors. The pt_regs' r3 will be updated to reflect
	* the actual r3 if possible, and a ptr to the error log entry
	* will be returned if found.
	*
	* If the RTAS error is not of the extended type, then we put it in a per
	* cpu 64bit buffer. If it is the extended type we use global_mce_data_buf.
	*
	* The global_mce_data_buf does not have any locks or protection around it,
	* if a second machine check comes in, or a system reset is done
	* before we have logged the error, then we will get corruption in the
	* error log. This is preferable over holding off on calling
	* ibm,nmi-interlock which would result in us checkstopping if a
	* second machine check did come in.
	*/
	static struct rtas_error_log fwnmi_get_errinfo(struct pt_regs regs)
	{
	unsigned long *savep;
	struct rtas_error_log h, errhdr = NULL;

	/* Mask top two bits */
	regs->gpr[3] &= ~(0x3UL << 62);

	if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
	printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
	return NULL;
	}

	savep = __va(regs->gpr[3]);
	regs->gpr[3] = savep[0]; /* restore original r3 */

	/* If it isn't an extended log we can use the per cpu 64bit buffer */
	h = (struct rtas_error_log *)&savep[1];
	if (!rtas_error_extended(h)) {
	memcpy(this_cpu_ptr(&mce_data_buf), h, sizeof(__u64));
	errhdr = (struct rtas_error_log *)this_cpu_ptr(&mce_data_buf);
	} else {
	int len, error_log_length;

	error_log_length = 8 + rtas_error_extended_log_length(h);
	len = max_t(int, error_log_length, RTAS_ERROR_LOG_MAX);
	memset(global_mce_data_buf, 0, RTAS_ERROR_LOG_MAX);
	memcpy(global_mce_data_buf, h, len);
	errhdr = (struct rtas_error_log *)global_mce_data_buf;
	}

	return errhdr;
	}

	/* Call this when done with the data returned by FWNMI_get_errinfo.
	* It will release the saved data area for other CPUs in the
	* partition to receive FWNMI errors.
	*/
	static void fwnmi_release_errinfo(void)
	{
	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
	if (ret != 0)
	printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
	}

	int pSeries_system_reset_exception(struct pt_regs *regs)
	{
	if (fwnmi_active) {
	struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
	if (errhdr) {
	/* XXX Should look at FWNMI information */
	}
	fwnmi_release_errinfo();
	}
	return 0; /* need to perform reset */
	}

	/*
	* See if we can recover from a machine check exception.
	* This is only called on power4 (or above) and only via
	* the Firmware Non-Maskable Interrupts (fwnmi) handler
	* which provides the error analysis for us.
	*
	* Return 1 if corrected (or delivered a signal).
	* Return 0 if there is nothing we can do.
	*/
	static int recover_mce(struct pt_regs regs, struct rtas_error_log err)
	{
	int recovered = 0;
	int disposition = rtas_error_disposition(err);

	if (!(regs->msr & MSR_RI)) {
	/* If MSR_RI isn't set, we cannot recover */
	recovered = 0;

	} else if (disposition == RTAS_DISP_FULLY_RECOVERED) {
	/* Platform corrected itself */
	recovered = 1;

	} else if (disposition == RTAS_DISP_LIMITED_RECOVERY) {
	/* Platform corrected itself but could be degraded */
	printk(KERN_ERR "MCE: limited recovery, system may "
	"be degraded\n");
	recovered = 1;

	} else if (user_mode(regs) && !is_global_init(current) &&
	rtas_error_severity(err) == RTAS_SEVERITY_ERROR_SYNC) {

	/*
	* If we received a synchronous error when in userspace
	* kill the task. Firmware may report details of the fail
	* asynchronously, so we can't rely on the target and type
	* fields being valid here.
	*/
	printk(KERN_ERR "MCE: uncorrectable error, killing task "
	"%s:%d\n", current->comm, current->pid);

	_exception(SIGBUS, regs, BUS_MCEERR_AR, regs->nip);
	recovered = 1;
	}

	log_error((char *)err, ERR_TYPE_RTAS_LOG, 0);

	return recovered;
	}

	/*
	* Handle a machine check.
	*
	* Note that on Power 4 and beyond Firmware Non-Maskable Interrupts (fwnmi)
	* should be present. If so the handler which called us tells us if the
	* error was recovered (never true if RI=0).
	*
	* On hardware prior to Power 4 these exceptions were asynchronous which
	* means we can't tell exactly where it occurred and so we can't recover.
	*/
	int pSeries_machine_check_exception(struct pt_regs *regs)
	{
	struct rtas_error_log *errp;

	if (fwnmi_active) {
	errp = fwnmi_get_errinfo(regs);
	fwnmi_release_errinfo();
	if (errp && recover_mce(regs, errp))
	return 1;
	}

	return 0;
	}